title: Mercury trends in predatory fish in Great Slave Lake: the influence of temperature and other climate drivers.
abstract: Here we report on trends in mercury (Hg) concentrations in lake trout (Salvelinus namaycush), burbot (Lota lota), and northern pike (Esox lucius) from Great Slave Lake, located in the Mackenzie River Basin (MRB) and investigate how climate factors may be influencing these trends. Hg concentrations in lake trout and burbot increased significantly over the early 1990s to 2012 in the two major regions of the lake; no trend was evident for northern pike over 1999-2012. Temporal variations in Hg concentrations in lake trout and burbot were similar with respect to timing of peaks and troughs. Inclusion of climate variables based on annual means, particularly temperature, improved explanatory power for variations in Hg over analyses based only on year and fish length; unexpectedly, the temperature coefficient was negative. Climate analyses based on growing season means (defined as May-September) had less explanatory power suggesting that trends were more strongly associated with colder months within the year. Inclusion of the Pacific/North American index improved explanatory power for the lake trout model suggesting that trends may have been affected by air circulation patterns. Overall, while our study confirmed previously reported trends of Hg increase in burbot in the MRB, we found no evidence that these trends were directly driven by increasing temperatures and productivity.
authors.affiliation: Aquatic Contaminants Research Division, Environment Canada , Saskatoon, Saskatchewan, Canada S7N 3H5.
authors.forename: Marlene
authors.initials: M
authors.lastname: Evans
authors.forename: Derek
authors.initials: D
authors.lastname: Muir
authors.forename: Robert B
authors.initials: RB
authors.lastname: Brua
authors.forename: Jonathan
authors.initials: J
authors.lastname: Keating
authors.forename: Xiaowa
authors.initials: X
authors.lastname: Wang
mesh_terms: D000818:Animals; D002170:Canada; D002980:Climate; D057231:Climate Change; D004784:Environmental Monitoring; D017859:Esocidae / Q000378:metabolism; D005399:Fishes / Q000378:metabolism*; D048388:Gadiformes / Q000378:metabolism; D005843:Geography; D019015:Geologic Sediments / Q000737:chemistry; D060106:Lakes; D016014:Linear Models; D008628:Mercury / Q000032:analysis*; D009132:Muscles / Q000378:metabolism; D011235:Predatory Behavior; D013696:Temperature; D013997:Time Factors; D014337:Trout / Q000378:metabolism; D014874:Water Pollutants, Chemical / Q000032:analysis
chemical_list: D014874:Water Pollutants, Chemical; D008628:Mercury